I have a small Koi pond with one pump that pushes the water through a filter. This pump is just plugged into the mains straight out of the box. It's been working perfectly for about 5 years but there isn't any transformer supplied with the pump, so does this means it runs off 220v? What safeguards are there if the pump shorts out?

No 1  the pump stops  No2 you eat boiled fish     No 3 depending on your electrical set up IE breakers/ safety trips etc     you pick the frazzled box off the wall

These things are (at least theoretically) well sealed, even so protect with a 15mA RCBO (500 Baht in HomePro) and it will be as safe as a 220V device in water can be.

 

We have two in the koi pond and several small ones in fish tanks, none have ever failed with water ingress (touch wood).

 

 

 

Thanks for the replies